The book celebrates Jewish radicalism from the Tsarist Empire to Poland and Germany, from London to New York. Fighting oppression and exploitation took numerous political forms, including left Zionism, Bundism and revolutionary Marxism. This inspiring radical tradition was ultimately checked by the callous indifference of capitalist governments to refugees and the horror of Auschwitz. However, its lessons must be passed on to inform working-class and anti-imperialist struggles in a world in crisis. This book recovers some of that long-neglected history. Before the Second World War, the majority of Jews were working-class and part of a wider struggle alongside their non-Jewish comrades on the left. To illuminate this background, the issue of Jewish identity is analysed along political, cultural and sociological lines. This is essential because, today, the claim of Israel and its apologists to represent Jews everywhere, the growth of the antisemitic far right and the approach of the left to the Jewish question are central issues. A knowledge of the breadth of Jewish resistance aids understanding of these debates.